I2C

Ton
 
Posts: 22
Joined: Sun Nov 16, 2014 4:35 pm

I2C

Tue Dec 02, 2014 9:28 pm

Anybody been working with I2C yet?
I had the i2c-0 device available, but i2cdetect 0 gave many IC's on almost all addresses, so somethiing goes not well yet.

Also, I strongly suspect Data and Clock are mixed up on the PCB layout.

darksoul
 
Posts: 45
Joined: Fri Nov 14, 2014 2:29 am

Re: I2C

Wed Dec 03, 2014 3:54 am

please give more information

Ton
 
Posts: 22
Joined: Sun Nov 16, 2014 4:35 pm

Re: I2C

Wed Dec 03, 2014 6:34 am

I changed the i2c section in VOCORE.dts to:

Code: Select all
      i2c@900 {
         compatible = "link,rt5350-i2c", "ralink,rt2880-i2c";
         reg = <0x900 0x100>;

         resets = <&rstctrl 16>;
         reset-names = "i2c";

         #address-cells = <1>;
         #size-cells = <0>;

         pinctrl-names = "default";
         pinctrl-0 = <&i2c_pins>;

         status = "okay";
      };

I did not add i2c support in kernel_menuconfig

In make menuconfig I added kernelmodules:
Code: Select all
   kmod-i2c-core
   kmod-i2c-ralink

(I think they were already present btw)

I added Makefile (https://dev.openwrt.org/browser/package ... s/Makefile) to
package/i2c-tools/Makefile
Then I did
Code: Select all
   make menuconfig
and selected
Utils
i2c-tools

after flash and reboot, I do

Code: Select all
insmod i2c-dev
and see the device /dev/i2c-0

Then I connected a YL-40 (https://brainfyre.wordpress.com/2012/10 ... le-review/) module
to 3v3 on pin PB18 (lower right corner, marked 3v3), GND, DATA, and SCLK

Then when you do

Code: Select all
i2cdetect 0

you expect only 0x48 to be present, but almost all adresses are present.
It seems something to do with pull-up, so:

Added a 4K7 pull up parallel to the 10K on YL-40, but that did not give any improvement.
Lowered VCC for YL-40 by putting diode inline, did not help too.

Any ideas?
Is there a second function of the pins that need to be disabled?
Is there more that I can check?


Concerning my thoughts about SDATA/SCLK swap:
The sch.pdf shows SCLK next to RESET in the black interface section,
but in the pdb.pdf it is SDATA next to RESET.
When I follow the tracks on the red layer of the pcb.pdf, and see the pinnumbers in
RT3530.pdf Table 1-2 196-Pin BGA Package Diagram Top View (right portion)
I see that sch.pdf seems to be right and pcb.pdf seems to be wrong.

silviop
 
Posts: 17
Joined: Mon Oct 20, 2014 11:51 am

Re: I2C

Mon Dec 15, 2014 9:58 pm

i2cdetect not work very well on i2c-ralink driver,
read this thread:

https://forum.openwrt.org/viewtopic.php?id=52191

Ton
 
Posts: 22
Joined: Sun Nov 16, 2014 4:35 pm

Re: I2C

Sun Dec 21, 2014 3:34 pm

Thanks, good information.

YL-40 is working now. Pins are swapped on pdf.
This is testsoftware:


Code: Select all
/* ------------------------------------------------------------------------ *
 *  PCF8591.c - check / test for YL-40 connected to Vocore                  *
 * ------------------------------------------------------------------------ *
 *
 * No error checking, just dumping values to the commandline
 * Vocore PDF VoCore.v1.0.pcb.pdf gives wrong information:
 * Pin next to RESET is CLK not DATA.
 * Pnnames are swapped. Correct is: Pin 1 GND, 2 RESET, 3 I2C_SCLK, 4 I2C_SD
 *
 * (c) 2014 Ton Augustin
 *
 * See: http://openwrt.pbworks.com/w/page/13164269/I2C
 *
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/i2c-dev.h>

/* from i2c.h */
#define I2C_SLAVE   0x0703   /* Change slave address         */


#define PCF8591_ADDR 0x48


//Control Register Defines for PCF8591
//AD Channels
#define PCF8591_ADC0 0x00
#define PCF8591_ADC1 0x01
#define PCF8591_ADC2 0x02
#define PCF8591_ADC3 0x03
//AD Channel Mask
#define PCF8591_CHMSK   0x03

//Auto Increment flag (0=disable, 1=enable)
#define PCF8591_AIF  0x04
 
//AD Channels Input modes
//4 Single Channels (Chan0=AIN0, Chan1=AIN0, Chan2=AIN0, Chan3=AIN0)
#define PCF8591_4S   0x00
//3 Diff Channels (Chan0=AIN0-AIN3, Chan1=AIN1-AIN3, Chan2=AIN2-AIN3)
#define PCF8591_3D   0x10
//2 Single Channels (Chan0=AIN0, Chan1=AIN1)
//1 Diff Channel    (Chan2=AIN2-AIN3)
#define PCF8591_2S_1D 0x20
//2 Diff Channels (Chan0=AIN0-AIN1, Chan1=AIN2-AIN3)
#define PCF8591_2D   0x30
//ChannelMode Mask
#define PCF8591_CHMDMSK  0x30
//Analog Output enable flag (0=disable, 1=enable)
#define PCF8591_AOUT 0x40

//Default Mode: ADC0, AutoIncr On, 4 Single Chan, AnalogOut Off
#define PCF8591_CTRL_DEF (PCF8591_ADC0 | PCF8591_AIF | PCF8591_4S)



int main(int argc, char *argv[]) {
  int file;
  int adapter_nr = 0; /* there is only one */
  char filename[20];
  unsigned long addr;
  int rc,ct;
  unsigned char data[1];
  unsigned char analog[12];


  sprintf(filename,"/dev/i2c-%d",adapter_nr);
  if ((file = open(filename,O_RDWR)) < 0) {
    /* ERROR HANDLING; you can check errno to see what went wrong */
    fprintf(stderr, "%s: failed to open %s, err=%d\n",argv[0],filename,file);
    exit(1);
  }

  addr = PCF8591_ADDR; /* The I2C address */
  if ((rc=ioctl(file,I2C_SLAVE,addr)) < 0) {
    /* ERROR HANDLING; you can check errno to see what went wrong */
    fprintf(stderr, "%s: addr ioctl failed, addr=0x%03lX, err=%d\n",argv[0],addr,rc);
    exit(1);
  } else
    //fprintf(stderr, "%s: ioctl set I2C_SLAVE addr=0x%03lX\n",argv[0],addr);

  while(1) {
   data[0] =   PCF8591_CTRL_DEF;
    if ( write(file,data,1) != 1) {
      /* ERROR HANDLING: i2c transaction failed */
      fprintf(stderr, "%s: i2c write failed\n",argv[0]);
      exit(1);
    }
    ct=read(file,analog,6);
    printf("Light:%3d Temp:%3d X:%3d Potmeter:%3d\r", analog[2],analog[3],analog[4],analog[5]); // Skip first bytes
  }

  return(0);
}




romeo_bbb
 
Posts: 4
Joined: Tue May 05, 2015 12:28 am

Re: I2C

Tue May 05, 2015 12:31 am

I get a byte on every single place so 00 01 02 03 04 05 ... etc. Did that happen to anybody? Never used I2C or anything similar before.

romeo_bbb
 
Posts: 4
Joined: Tue May 05, 2015 12:28 am

Re: I2C

Tue May 05, 2015 1:12 am

I am getting

0 1 2 3 4 5 6 7 8 9 a b c d e f
00: 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30: 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
40: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50: 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
60: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70: 70 71 72 73 74 75 76 77

Did anybody get this? What am I doing wrong?

Vonger
 
Posts: 746
Joined: Sun Oct 19, 2014 6:00 am

Re: I2C

Tue May 05, 2015 2:57 am

1. Check if you have 4.7K pull up resistors on both SCL and SDA.
2. i2cdetect should be called with parameter "-r"

romeo_bbb
 
Posts: 4
Joined: Tue May 05, 2015 12:28 am

Re: I2C

Tue May 05, 2015 3:45 am

I am using -r. And I am using YL-40 Image. It has the resistors on the board, no?

Vonger
 
Posts: 746
Joined: Sun Oct 19, 2014 6:00 am

Re: I2C

Fri May 08, 2015 6:40 am

I think you might use old openwrt version. In old openwrt, i2c-ralink driver has bug. Latest openwrt version will fix such issue.
and download i2c-tools from 14.04 barrier breaker/oldpackages then install manually.

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